Leishmania major: in vitro and in vivo anti-leishmanial activity of paromomycin ointment (Leshcutan) combined with the immunomodulator Imiquimod

Paromomycin at 25, 50 and 100 microg/ml, inhibited the growth of Leishmania major amastigotes by 34.5%, 61.2%, 74.9% and 85.4%, 89.9%, 95.7% on the 2nd and the 4th day of treatment in culture, respectively. Methylbenzethonium chloride at 0.1 and 0.5 microg/ml and Imiquimod at 5 and 10 microg/ml, administered separately, inhibited the parasite development by 39.5% and 65.2% and 31.5% and 47.7%, respectively. Imiquimod (5-10 microg/ml) combined with either paromomycin (25, 50 and 100 microg/ml) or methylbenzethonium chloride (0.1 and 0.5 microg/ml) showed an anti-leishmanial additive effect. A 10 day topical treatment, twice daily, with an ointment containing 15% paromomycin and 12% methylbenzethonium chloride (Leshcutan), either undiluted or diluted 1:5 in soft white paraffin combined with 5% Imiquimod cream (Aldara), was as effective as Leshcutan given alone. The present study suggests that a combination of Aldara and Leshcutan is as effective as Leshcutan given alone in the topical treatment of CL caused by L. major.